/Engine/Source/Runtime/GeometryFramework/Public/Components/DynamicMeshComponent.h
This delegate fires when the mesh vertices have been changed via anFMeshVertexChange
typedef TMulticastDelegate_ThreeParams< void, [UDynamicMeshComponent](API\Runtime\GeometryFramework\Components\UDynamicMeshComponent) *, const [FMeshVertexChange](API\Runtime\GeometryFramework\Changes\FMeshVertexChange) *, bool > FMeshVerticesModified